The Congolese hosts kicked off proceedings in ideal fashion. Striker Ramos Kashala Wanet opened the scoring in the third minute of the match when he blasted the ball beyond Pirates stopper Sipho Chaine.
The Buccaneers pushed to level things up, with forward Evidence Makgopa carving out a chance around 15 minutes in, only for his shot to be denied by a sharp save from Lupopo keeper Simon Ommossola.
However, the hosts suffered a setback just ten minutes shy of halftime. Nigerian midfielder Rafael Oliseh limped off injured, making way for substitute Dramane Kambou, as the teams went down the tunnel for the halftime break.
Looking to inject energy into the tie, Pirates coach Abdeslam Ouaddou brought on Oswin Appollis and Thalente Mbatha in the second stanza and it nearly paid off immediately.
Appollis' effort on the hour mark had Ommossola beat, but it went just wide of the right post.
But the hosts were unperterbed. They doubled their lead through substitute Dramane Kambou in the 70th minute when he pounced on a loose ball and beat a hapless Chaine.
The Soweto giants then left themselves with a mountain to climb in the second leg at home when they conceded a third goal via the boot of teenager Jean Benoit Tukumban.